[modbus] README: timeBetweenTransactionsMillis default fix w/ serial (#4457)
[modbus] README: timeBetweenTransactionsMillis default fix w/ serial (#4457)

See constructConnectionPool in ModbusManagerImpl
https://github.com/openhab/openhab2-addons/blob/master/addons/io/org.openhab.io.transport.modbus/src/main/java/org/openhab/io/transport/modbus/internal/ModbusManagerImpl.java#L294

PaperUI default is also 35 ms
https://github.com/openhab/openhab2-addons/blob/master/addons/binding/org.openhab.binding.modbus/ESH-INF/thing/bridge-serial.xml#L124

Signed-off-by: Sami Salonen <b82ddbcee3fd00ee4d3f5b618a47b3246b53c3ed@gmail.com>
digitaldan/openhab2,clinique/openhab2,digitaldan/openhab2,Snickermicker/openhab2,theoweiss/openhab2,afuechsel/openhab2,clinique/openhab2,Snickermicker/openhab2,clinique/openhab2,gerrieg/openhab2,gerrieg/openhab2,Snickermicker/openhab2,afuechsel/openhab2,Snickermicker/openhab2,gerrieg/openhab2,afuechsel/openhab2,gerrieg/openhab2,digitaldan/openhab2,theoweiss/openhab2,theoweiss/openhab2,clinique/openhab2,digitaldan/openhab2,theoweiss/openhab2